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ZEWDIS

6-month old male pygmy hippopotamus (Choeropsis liberiensis)

February 14, 2020
Eric T Hostnik, DVM, MS, DACVR-DI, DACVR-EDI
Gabriella L. Flacke, DVM, MSc, PhD, Zoo Miami
James G. Johnson III, DVM, MS, CertAqV, DACZM, Saint Louis Zoo
Marisa Bezjian, DVM, Zoo Miami
Gwen E. Myers, DVM, Zoo Miami

Chronic nasal discharge and upper respiratory stertor

Transverse CT image at the level of the bullaecaption

History/Clinical Findings:

The pygmy hippo calf was noted to exhibit respiratory stertor since shortly after birth, but was otherwise healthy, nursing, and gaining weight appropriately. At approximately 1 month of age the calf was first noted to exhibit a behavior akin to a reverse sneeze, especially after nursing. Occasionally white fluid would come out of the nostrils. At about 3 months of age the calf developed intermittent bilateral mucopurulent nasal discharge. Culture was performed and targeted antibiotic therapy was instituted. While on oral antibiotics the nasal discharge improved; however the stertorous breathing and reverse sneeze-type activity continued, especially after eating. Rule outs included oral-nasal fistula, soft palate defect, nasal foreign body, or congenital dysphagia. An examination under anesthesia was performed to conduct further diagnostics and evaluate the oral cavity and nasal passages.

Transverse CT images of the head

Vimago computed tomography of the skull was performed. No intravenous contrast medium was administered.

There is a defect within the soft palate. The defect is characterized by a communication between the nasopharynx and oropharynx. The soft palate defect starts at the level of the caudal hamulus with an approximately 6.7 mm gap between the right and left aspects of the palatal margins. The defect continues caudally resulting in a large common laryngopharyngeal space. The soft palate is lacking at the level of the tympanic bullae and the external orifice of the Eustachian tubes.

The tympanic bullae have two compartments; a small pneumatic portion and a larger cavern with numerous small mineral septations. There is soft tissue that fills all portions of the middle ear; the left side is more affected. The right tympanic wall is thinner than the left tympanic bulla, especially axially. The soft palate defect at the level of the tympanic bullae is 9.4 mm. The length of the soft palate defect is approximately 4.6 to 4.8 cm from the caudal aspect of the current palate to the level of the epiglottis.

The patient is intubated. There is a small amount of bilateral heterogeneous soft tissue within the nasal passage; the soft tissue is adherent to the mucosa of the turbinates. The teeth are unremarkable. The dental buds are unremarkable. There is mild blunting of the nasal turbinates bilaterally. The ethmoid turbinates are unremarkable. There is also asymmetric soft tissue within the nasal passages. The right maxillary recess contains soft tissue. There is a metallic transponder within the muscle of the right caudal neck.

1. Soft palate congenital defect with failure of midline closure. The defect results in the communication of the nasopharynx and oropharynx.

2. Bilateral otitis media; there is right-sided septic osteitis.

3. Bilateral rhinitis, nasal mucous, hemorrhage, and/or food materials from reflux.

Rhinoscopy and laryngoscopy were performed for direct visualization of the palatal defects and plan for surgical correction. The young pygmy hippo underwent a palatoplasty to correct the defect between the nasopharynx and oropharynx. This is the first reported case of a soft palate defect in this species.